About leaving a spring set...
Do you have an automobile? When you park it you will have some valves open with the springs compressed. Do you remove the valve covers every time you park your car and back out the rocker arm stud? Absolutely not.
A spring is weakened by cycling it.
Imagine a steel lid on a can of beans. You remove the lid with a can opener, eat the beans of course then bend the can lid in half and leave it. Will it weaken by being bent? No. It will be weakened by flattening it back out then bending it again and on and on.
Springs are "tempered" to have elasticity. You can compress them or relax them without weakening them. But cycling them will fatigue them. And, it takes a VERY high number of cycles to bring it to failure.
But hey, don't take my word for it. Check with spring designers and manufacturers. They'll tell you the same thing.
You can leave your firearm cocked and the magazine full without worry of weakening the spring. It's physics not Internet forum nonsense.